I have a 97' YZ 250. I have owned it for about a year and it runs good all the time. Last Saturday though I ran out of gas on a trail. I was able to get back to my truck on another bike but I didn't have any premixed gas. I however got some regular 91 gas and filled up a gatorade bottle 3/4's full. I then got some 2t oil from the ranger that they use for their weed wackers. I just "eyeball" mixed it to what I thought looked good. I then put it in my bike and was able to get back to my truck (about a 3 minute ride back to the truck). The bike then sat at my house for 1 week. Now 1 week later, I filled up the tank to the top with fresh gas. (I did not drain the gas that was left in the tank) The bike started up fine but it fouled the plug within minutes. I took out the plug, cleaned it, put it back. It then would start fine put would die and foul the plug again within about a minute. My question: Should I just drain the gas and be good to go? and/or Did that crap gas that I left in the bike for 1 week gum up the carb/jets, and should I take out the carb and clean it?